Title of Invention

HONEYCOMB CARRER FOR EXHAUST GAS CLARIFICATION CATALYST AND METHOD FOR PRODUCTION TREREOF

Abstract to provide a honeycomb carrier to support a catalyst to clean e.g. an exhaust gas of an automobile particularly containing NOx, which is excellent in heat 5 resistance, thermal shock, resiatance, mechanica1 strength and thermal decomposition resistance and has a great corrosion resistance to a catalyst, and is thus capable of being used with stability for a long period of time, and a procege for its production. 10 The material for the honeycojnb carrier is an aluminum magnesium titanate sintered product obtained by firing at from 1,000 to l,700°C a molded product formed from a raw material mixcture eomprising 100 parts by mass, as calculated as oxides, of a mixture comprising a Mg- 15 containing compound, an Al-containing compound and a Ti- containing compound in the same metal component ratio as the metal component ratio ot Mg, Al and Ti in an aluminium magnesium titanate represented by the empirical formula MgxAl2(1+x)Ti(1+x)O5 fwherein 0<X<l) , and from 1 to 10 parts 20 by mass of an alkali feldspar represented by the empirical formula (NayK1-y)AlSi3O8 (wherein XXX) .
Full Text 1
DESCRIPTION
HONEYCOMB CARRIER FOR EXHAUST GAS-CLEANING CATALYST AND
METHOD FOR PRODUCTION THEREOF
5
TECHNICAL FIELD
The present invention relates to a carrier to
support a catalyst to clean various exhaust gases
particularly an exhaust gas ot an automobile containing
10 NOx, and a process for its production.
BACKGROUND ART
The chief characteristics required of a honeycomb
carrier to support a catalyst to be used for an apparatus
15 for cleaning an automobile exhaust gas which, is
particularly widely used at present among various
apparatuses for cleaning an exhaust combustion gas, are
gol-called heat resistance and thermal shock resistance.
A high, heat reaistance is required since the honeycomb
20 carrier will be exposed to a high temperature of 650º C or
higher by sudden heat generation due to a catalytic
oxidation reaction of unburned hydrocarbons or carbon
monoxide in the exhaust gas. Further, the thermal shock
resistance is a quality to be resistant to cracks or
25 breakage by a thermal stress caused in the honeycomb due
to a temperature increase by such sudden heat generation.
With respect to the thermal shock resistance, the smaller

2
the therma1 expansion coefficient, the greater the
endurance temperature difference.
So as to meet such requirements as heat resistance
and thermal shock resistance various ceramics have been
5 proposed, as a material for a honeycomb carrier, but a
cordierite material has been chiefly used. The primary
reason why a cordierite material is used is that
cordierite has a so high thermal resistance as l,400ºC,
and it has an extremely small thermal expansion
10 coefficient and high thermal shock resistance among
ceramics as well.
However, although a cordierite material as a
material for a honeycomb carrier has rather excellent
quality with respect to heat resistance and thermal shock
15 resistance, it is highly disadvantageous when used as a
catalyst carrier for cleaning an exhaust gas containing a
nitrogen oxide (NOx) , the removal of which is "urgently
required from an environmental viewpoint. That is,
usually a catalyst containing an alkali metal or alkaline
20 earth metal component is used as a catalyst to remove NOx
in the exhaust gas. In such a case, a part of the alkali
metal or alkaline earth metal is infiltrated into
cordierite as a carrier and reacts with cordierite at a
high temperature, and such leads to a deterioration of
25 cordierite and loss of the catalyst as well, and thus
causes a decrease of removal of NOx in the exhaust gas.
In order to prevent such a phenomenon, a method of

3
covering the surface of the catalyst with silica (SiO2),
and the like, have been proposed, but an extra step will
be required, and an increase in the cost will be
inevitable.
5 On the other hand, in a system wherein a fuel is
directly jetted into an engine or in a system wherein a
fuel is diluted and burned, which is becoming the main
stream of a burning system of an automobile in recent
years from a viewpoint of improvement in mileage and from
10 an environmental, viewpoint, removal of NOx in the exhaust
gas is a particularly important concern as compared with
removal of hydrocarbons and carbon monoxide. Accordingly,
as a material for a honeycomb carrier to support a
catalyst to clean an exhaust gas, a material which
15 replaces cordierite has been strongly desired.
As materials other than cordierite, WO01/037971
discloses ceramics such as silicon carbide, silicon
nitride, mullite, aluminum titanate and lithium aluminum
silicate. However, they are all insufficient as a
20 material for the honeycomb Carrier. That is, silicon
nitride, mullite, etc. have a high thermal expansion
coefficient and are poor in thermal shock resistance.
Further, silicon nitride, lithium aluminum silicate, etc.
are insufficient in view of heat resistance.
25 Aluminum titanate has excellent stability even at a
high temperature exceeding l,700ºC, an extremely email
thermal expansion coefficient and excellent thermal shock

4
resistance. However, it has such a drawback as small
mechanical strength, since the anisotropy of its crystal
structure is significant, whereby slip is likely to occur
at the crystalline interface by a thermal stress.
5 Resultingly, a honeycomb having a small wall thickness
and a high cell density is hardly produced with it, and
its use as a carrier for an exhaust gas-cleaning catalyst
to which a load of mechanical vibration will be applied
at a high temperature, tends to be difficult. Further,
10 such aluminum titanate, etc usually have decomposition
points within a temperature range Of from 800 to l,200ºC,
and they can not be used continuously for a long time in
a region including such a temperature range.
15 DISCLOSURE OF THE INVENTION
The present invention provides a honeycomb carrier
which is a carrier tc support a catalyst to clean
particularly an exhaust gas of an automobile containing
NOx, which is excellent in heat resistance, thermal shock
20 resistance, mechanical strength and thermal decomposition
resistance and has corrosion resistance against a
catalyst containing an alkali component, and which is
thereby excellent in durability so that it will not
deteriorate even in a long term use, and a process for
25 its product ion.
In order to solve the above problems, the present
inventors have conducted extensive studies on aluminum

5
magnesium titanate and aluminum titanate and as a result,
made the fallowing discoveries. That is, a sintered
product obtained by firing a mixture comprising a mixture
comprising a Ti-containing compound, an Al-containing
5 compound and a Mg-containing compound in a predetermined
ratio to form aluminum magnesium titanate, or a mixture
comprising a Ti-containing compound and an Al-containing
compound in a predetermined ratio to form aluminum
titanate, and a specific alkali feldspar, an oxide of a
10 spinel structure containing Mg, or MgO or a Mg-containing
compound which can be converted to MgO by firing added in
a predetermined ratio, is very excellent as a carrier to
support a catalyst to clean an exhaust gas of an
automobile.
15 Accordingly, it has been found that a honeycomb
carrier made of the above sintered product of the present
invention has high heat resistance and thermal shock
resistance attributable to low thermal expansion
properties and further has high mechanical strength and
20 high thermal decomposition resistance as different from a
conventional aluminum magnesium titanate sintered product
or aluminum titanate sintered product, and that the
sintered product can be used with stability for a long
period of time without deterioration as a conventional
25 cordierite material, even when a catalyst containing an
alkali metal or alkaline earth metal component is used as
a catalyst for removal of NOx.

6
The present invention has been accomplished on the
basis of these discoveries and provides the following:
(l) A honeycomb carrier for an exhaust gas-cleaning
catalyst which is a honeycomb carrier to support a
5 catalyst to clean an exhaust gas, characterized in that
the material for the honeycomb carrier is an aluminum
magnesium titanate sintered product obtained by firing at
from 1,000 to l,700ºc a mixture comprising 100 parts by
mass, as Calculated as oxides, of a mixture comprising a
10 Mg-containing compound, an Al-containing compound and a
Ti-containing compound in the, same metal component ratio
as the metal component ratio of Mg, Al and Ti in an
aluminum magnesium titanate represented by the empirical
formula MgxAl2(1-x)O5 (wherein O 15 10 parts by mass of an alkali feldspar represented by the
empirical formula (NayK1-y) AlSi9O8 (where in ***OXXXyXXXl).
(2) A honeycomb carrier fox an exliaust gas-cleaning
catalyst which is a honeycomb carrier to aupport a
catalyst to clean an exhaust gas, characterised in that
20 the material for the honeycomb carrier is an aluminum
titanate sintered product obtained by firing at from
1,250 to l,700ºC a raw material mixture comprising 100
parts by mass of a mixture (hereinafter referred to as
component X) comprising TiO2 and Al2O3 in a molar ratio of
25 the farmer/the latter being 40 to 60/60 to 40, and from 1
to 10 parts by mass of an alkali feldspar represented by
the empirical formula (NayK1-y)AlSi3O8 {wherein XXX), an

7
oxide of a spinel structure containing Mg, or MgO or a
Mg-containing compound which can be converted to MgO by
firing (hereinafter referred to as component Y).
(3) The honeycomb carrier according to the above (2),
5 wherein the component Y is a mixture comprising an alkali
feldspar represented by {NayK1-y) AlSi3O8 (wherein XXX),
and an oxide of a spinel structure containing Mg and/or
MgO or a Mg-containing compound which can be converted to
MgO by firing.
10 (4) The honeycomb carrier according to any one of the
above (1) to (3), which has a wall thickness of from 0.05
to 0.6 mm, a cell density of from 15 to 124 cells/cm2, a
porosity of the partition wall of from 20 to 50%, and a
thermal expansion coefficient of at most 3.O x lO-6K-1.
15 (5) The honeycomb carrier according to any one of the
above (1) to (4), wherein the catalyst contains an alkali
metal or alkaline earth metal component to remove NOx in
the exhaust gas.
(6) The honeycomb carrier according to any one of the
20 above (1) to (5), wherein the exhaust gas is an axhaust
gas of an automobile of a system wherein a fuel is
directly jetted into an engine or of a system wherein a
fuel is diluted and burned.
(7) A process for producing a honeycomb carrier for an
25 exhaust gas-cleaning catalyst, characterized by preparing
a raw material mixture comprising 100 parts by mass, as
calculated as oxides, of a mixture comprising a Mg-

8
containing compound, an A1-containing compound and a Ti-
containing compound in the same metal component ratio as
the metal component ratio of Mg, Al and Ti in an aluminum
magnesium titanate represented by the empirical formula
5 MgxAl2(2-x)Ti(1+x)O5 (wherein O by mass of an alkali feldspar represented by the
empirical formula (NayK1-y)AlSi3O8 (wherein ***XXX), adding
a molding assistant to the raw material mixture, followed
by kneading to plasticize the raw material mixture to
10 make it extrueion-processable, and then extrusion
processing it into a honeycomb body, followed by firing
at from 1,000 to 1,700ºC.
(8) A process for producing a honeycomb carrier for an
exhaust gas-cleaning catalyst, characterized by preparing
15 a mixture comprising 100 parts by mass of a mixture
(hereinafter referred to as component X) comprising TiO2
and A12O3 in a molar ratio of the former/the latter being
40 to 60/60 to 40, and from 1 to 10 parts by mass of an
alkali feldspar represented by the empirical formula
20 (NayK1-y) AlSi3O8 (wherein XXX), an oxide of a spinel
structure containing Mg, or MgO or a Mg-containing
compound which can be converted to MgO by firing
(hereinafter referred to as component Y), adding a
molding assistant to the mixture, followed by kneading to
25 plasticize the mixture to make it extrusion-procesable,
and extrusion processing it into a honeycomb body,
followed by firing at from l,250 to l,700ºC.

9
(9) The process for producing a honeycomb carrier for an
exhaust gas-cleaning catalyst according to the above (7)
or (8), wherein the average particle size of each
component contained in the raw material mixture is at
5 most 10 µm.
(10) A method for cleaning an exhaust gas, which
comprises contacting the exhaust gas to a honeycomb
carrier Supporting a catalyst to clean an exhaust gas,
characterized in that the material for the honeycomb
10 carrier is an aluminum magnesium titanate sintered
product obtained by firing at from 1,000 to l,700ºC a
mixture comprising 100 parts by mass, as calculated as
oxides, of a mixture comprising a Mg-containing compound,
an Al-containing compound and a Ti-containing compound in
15 the same metal component ratio as the metal component
ratio of Mg, Al and Ti in an aluminum magnesium titanate
represented by the empirical formula MgxAl2(1-x)Ti(1+x)O5
(Wherein O alkali feldspar represented by the empirical formula
20 (NAYK1-Y)ALSI3O8 (wherein XXX).
(11) A method for cleaning an exhaust gas, which
comprises contacting the exhaust gas to a honeycomb
carrier supporting a catalyst to clean an exhaust gas,
characterized in that the material for the honeycomb
25 carrier is an aluminum titanate aintered product obtained
by firing at from 1,250 to l,700ºC a raw material mixture
comprising 100 parts by mass of a mixture (hereinafter

10
referred to as component X) comprising TiO2 and Al2O3 in a
molar ratio of the former/the latter being 40 to 60/60 to
40, and from l to 10 parts by mass of an alkali feldspar
represented by the empirical formula (NayK1-Y) AlSi3O8
5 (wherein XXX), an oxide of a spinel structure
containing Mg, or MgO or a Mg-containing compound which
can be converted to MgO by fixing (hereinafter referred
to as component Y).
10 EFFECTS OP THE INVENTION
The honeycomb carrier of the present invention has
high heat resistance and thermal shock resistance
attributable to low thermal expansion properties and
further, has high mechanical strength and excellent
15 thermal decomposition resistance as different from a
conventional aluminum magnesium titanate sintered product
or aluminum titanate sintered product, and ia further
excellent in corrosion resistance against a catalyst,
Reaultingly, it is useful as a carrier to support a
20 catalyst to clean any exhaust gas from a combustion
source of either a stationary body or a mobile body,
particularly an exhaust gas of an automobile containing
NOx.
The reason why the honeycomb carrier of the present
25 invention has high heat resistance and thermal shock
resistance and further has excellent mechanical strength
and thermal decomposition resistance, and does not

11
deteriorate even when used as a carrier Eor a catalyst
containing an alkali metal component to clean an exhaust
gas containing NOx, is not necessarily clearly understood.
However, the following reasons are estimated,
5 respectively in a case where the honeycomb carrier of
the present invention is made of an aluminum magnesium
titanate sintered product and a case where the honeycomb
carrier of the present invention is made of an aluminum
titanate sintered product.
10 (A) In a case where the honeycomb carrier of the present
invention is made of an aluminum magnesium titanate
sintered product, the crystals of aluminum magnesium
titanate as the basic structure are formed in a state
where, by the presence of an alkali feldspar in their
15 production process, the alkali feldspar becomes a liquid
phase, whereby dence crystals will be formed, and the
mechanical strength will be improved, And, the Si
component containt in the alkali feldspar will be solid
salubilized in the crystal lattice of aluminum magaesium
20 titanate when, aluminum magnasium titanate is formed by
firing, and as the Si solid-aolutoilization state, two
types, i.e. si having a coordination number of 6 and
solid-solubillized in the interior of the crystal grains
and Si having a coordination number of 4 and solid
25 solubilized at the surface portion of the crystal grains,
are considered. This is confirmed also by results by NMR
(nuclear magnetic resonance) measurement such that si in

12
the aluminum magnesium titanate crystals is present in
two states of one having a coordination number of 6 and
one having a coordination number of 4.
Namely, Si to be solid-solubilized in the interior
5 of the crystal grains of aluminum magnesium titanate has
a coordination number of 6 and is tetravalent, and will
form a pair with bivalent Mg which also has a
coordination number of 6 so that the pair will be
aexivalent in total and will be substituted for adjacent
10 two trivalent Al (sexivalent in total having a
coordination number of 6). The reason for this will be
explained from the correlation of ionic radii in addition
to the maintained balance of electrical charge. That is,
the ionic radii of Si2+ and Mg2+ are 0.54 Å and 0.86 Å,
15 respectively. The average ionic radius of the two will
be 0.70 Å which is close to 0.68 Å i.e. the ionic radius
of Al3+, whereby the occupation of two Al3+ by the pair of
Si0+ and Mg2+ will be in a solid solution state which is
more stable from the viewpoint of energy. Thus, it is
20 considered that by the simultaneous presence of si and Mg,
diffusion of ions among the respective cations in
aluminum magnesium titanate can be suppressed even at a
high temperature, and a stable crystal structure can be
secured, whereby excellent thermal decomposition
25 resistance will be obtained.
On the other hand Si to be solid-solubilized at the
surface portion of the crystal grains of aluminum

13
magnesium titanate has a coordination number of 4 not 6.
This is considered to be because Si at the surface
portion has a coordination, number of 4, to which oxygen
is more stably bonded, since the number of cations with
5 which oxygen is shared, Which are so-called counterparts,
is small. Accordingly, Si to be solid-solubilized at the
surface portion of the crystal grains is in a state of
mimetically coating the crystals of aluminum magnesium
titanate. Thus, it is considered that the honeycomb
10 carrier of the present invention, even when used as a
carrier for a catalyst containing an alkali metal, has
excellent corrosion resistance against erosion of the
carrier by an alkali component at a high, temperature,
whereby it will not deteriorate even in a long term use.
15 (B) In a case where the honeycomb carrier of the present
invention is made of an aluminum titanate sintered
product, by incorporation of an alkali feldspar to the
mixture for forming aluminum titanate, the alkali
feldspar which becomes a liquid phase in the vicinity of
20 the temperature for forming aluminum titanate is present,
and thus the reaction for forming aluminum titanate will
take place in the liquid phase, whereby dense crystals
will be formed, and the mechanical strength will be
improved. And, the Si component contained in the alkali
25 feldspar will be solid-salubilized in the crystal lattice
of aluminum titanate and substitute for Al. Si has a
smaller ionic radius than Al, whereby the bond length

14
with surrounding oxygen atoms is shorter, and the lattice
constant tends to be small as compared with pure aluminum
titanate. Accordingly, it is considered that the
sintered product to be obtained will have a stabilized
5 crystal structure and exhibit very high thermal stability,
and have significantly improved thermal decomposition
resistance.
Further, when an oxide of a spinel structure
containing Mg, ot MgO or a Mg-containing compound which
10 can be converted to MgO by firing is added to the mixture
forming aluminum titanate, a dense sintered product will
be obtained, and a sintered product having very high
mechanical strength as compared with pure aluminum
titanate will be formed.
15 Still furthar, when an alkali feldspar, and an oxide
of a spinel structure and/or MgO or a Mg-containing
compound. which can be converted to MgO by firing are
simultaneously added to the mixture forming aluminum
titanate, Si contained in the alkali feldspar and Mg
20 contained in the oxide of a spinel structure and MgO or
the Mg-containing compound which can be converted to MgO
by firing, will be substituted for mainly Al sites in
aluminum titanate. When such elements are added by
themselves, a bivalent (Mg) or tetravalent (Si) element
25 will be substituted for Al sites where a fundamentally
trivalent electrical charge balsance is maintainad.
Accordingly, it is considered that so as to maintain the

15
electrical charge balance, when Mg is added, oxygen is
discharged out of the system to cause an oxygen defect to
maintain the electrical charge balance, and when Si is
added, as si is tetravalent, fundamentally tetravalent Ti
5 is reduced to trivalent to maintain the alectrical change
balance.
On the other hand, Mg has an electrical charge
amaller by 1 than Al and Si has an electrical charge
larger by 1 than Al. Accordingly, it is considered that
10 the electrical charge balance can be maintained by
simultaneously adding the alkali feldspar and the oxide
of a spinel structure and MgO or the Mg-containing
compound which can be converted to MgO by firing, whereby
Si can be solid-solubilized without influence over other
15 sintered product-constituting elements.
Particularly, in such a case, it is considered that
when the alkali feldspar, the oxide of a spinel structure
and MgO or the Mg-containing compound which can be
converted to MgO by firing are added in a ratio close to
20 an equimolar ratio, the additives can be present more
stably as compared with a case where they are added by
themselves. It is considered that from these reasons,
they synergiscically function, whereby an aluminum
titanate sintered product, which has significantly
25 improved. strength as compared, with a case where the
additives are used by themselves, low thermal expansion,
properties which aluminum titanate fundamentally has, and

16
high mechanical strength, and yet has improved thermal
decomposition resistance, will be formed.
Further, the reason, why the honeycomb carrier of the
present invention has excellent corrosion resistance
5 against a catalyst containing an alkali component is
estimated as follows. Firstly, in the case of a
honeycomb carrier made of aluminum titanate obtained by
firing a raw material mixture containing an alkali
feldspar, when aluminum titanate is formed, the potassium
10 component contained in the alkali feldspar has been
already present outside the aluminum titanate crystal
system (present at the Crystalline interface).
Accordingly, when a catalyst containing an alkali
component is supported so that the alkali component is in
15 contact wich the honeycomb carrier, the osmotic pressure
of potassium to the honeycomb carrier tends to be low,
and resultingly infiltration of potassium into the
carrier will be inhibited.
On the other hand, in the case of aluminum titanate
20 obtained by firing a raw materia1, mixture containing an
oxide or a spinel structure containing Mg, or MgO or a
Mg-containing compound which can be converted to MgO by
firing, by the presence of a Mg (one of alkaline earth
metals) component which is a basic element, the aluminum
25 titanate sintered product tends to have a decreased
acidity, whereby its reactivity with the alkali component
which is a base (one of alkali metals) in the catalyst

17
tends to be low.
Further, in the case of aluminum titanate obtained,
by firing a raw material mixture containing both an
alkali feldspar, and an oxide of a spinel structure
5 containing Mg, or MgO or a Mg-containing compound which
can be converted to MgO by firing, it is considered that
both the above mechanisms will synergistically function,
whereby very excellent corrosion resistance against an
alkali component will be achieved.
10
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows the changes with time of the remaining
ratios a of aluminum magnesium titanate with respect to
the sintered products in Example l-l of the present
15 invention and Comparative Example l-l.
Fig. 2 shows the changes with time of the remaining
ratios β of aluminum titanate with respect to the
eintered products in Examples 2-1 and 2-2 of the present
invention and Comparative Example 2-1.
20
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, as the material for the
honeycomb structure catalyst carrier, the following
aluminum magnesium titanate sintered product (A) or
25 aluminum titanate sintered product (B) ie used.
(A) Aluminum magnesium titanate sintered product.
An aluminum magnesium titanate sintered product

18
obtained by firing at from 1,000 to l,700ºC a raw
material mixture comprising 100 parts by mass, as
calculated as oxides, of a mixture comprising a Mg-
containing compound, an Al-containing compound and a Ti-
5 containing compound in the same metal component ratio as
the metal component ratio of Mg, Al and Ti in an aluminum
magnesium titanate represented by the empirical formula
MgxAl2(1-x)Ti(1+x)O5 (Wherein 0 by mass of an alkali feldspar represented by the
10 empirical formula (NayK1-y)AlSi3O8 (wherein XXX).
The above Mg-containing compound, Al-containing
compound and Ti-containing compound to be used as the raw
materials, are not particularly limited so long as they
are components capable of synthesizing aluminum magnesium
15 titanate by firing. The Mg-containing compound, Al.
containing compound and Ti-containing compound may not
necessarily be separate compounds respectively, and may
be a compound containing two or more metal components.
Such, raw material compounds may usually be suitably
20 selected among those to be used as raw materials for
various ceramics, such as alumina ceramics, titania
ceramics, magnesia ceramics, aluminum titanate ceramics,
magnesium titanate ceramics, spinel ceramics and aluminum
magnesium titanate ceramics. Specific examples of such
25 compounds include oxides such, as Al2O3, TiO2 and MgO,
composite oxides cantaining at least two types of metal
components, such as MgAl2O4, Al2TiO3, MgTi2O3, and various

19
spinel structures containing Mg and Ti, compounds
containing one or more metal components selected from the
group consisting of Al, Ti and Mg (such as carbonates,
nitrates or sulfatas).
5 The blend ratio of the Mg-containing compound, the
Al-containing compound and the Ti-containing compound is
such that the ratio of the metal components contained in
these compounds would be a ratio similar to, preferably
the same ratio as, the metal component ratio of Mg, Al
10 and Ti in aluminum magnesium titanate represented by the
above empirical formula MgxAl2(1-x)Ti(1+x)O5 (wherein O By using the above respective compounds ae mixed in such
a ratio, it is possible to obtain aluminum magnesium
titanate having the same metal component ratio as the
15 metal component ratio in the mixture used as the raw
material.
When a honeycomb filter of the present invention is
to be obtained, it is necessary to incorporate an alkali
feldspar as an additive to the above mentioned mixture
20 comprising the Mg-containing compound, the Al-containing
compound and the Ti-containing compound. The alkali
feldspar not only serves as a sintering assistant for
aluminum magnesium titanate, but also plays a role of
adding a Si component to the aluminum magnesium titanate,
25 and it is represented by the empirical formula
(NayK1-y)AlSi3O5. IN the formula,y satisfies XXX),
preferably 0.lXXX), particularly preferatoly 0.l5XXX0+85

20
An alkali feldspar having value y within this range, has
a low melting point and is particularly effective for
promoting the sintering of aluminum magnesium titanate.
The amount of the alkali feldspar to be used, is
5 usually from about 1 to 10 parts by mass, preferably from
about 3 to about 5 parts by mass, per 100 parts by mass
of the total amount of the Mg-containing compound, the
Al-containing compound and the Ti-containing compound to
be used as the raw materials, as calculated as the
10 respective oxides. In such a case, the total amount of
the raw material mixture as calculated as oxides, is the
mass after carrying out heat treatment to remove moisture
or organic substances contained in the above raw material
mixture, or when pres in tearing is carried out, the mass
15 before the main firing after the presintering.
To the raw material mixture having an alkali
feldspar added to the mixture comprising the Mg-
containing compound, the Al-containing compound and the
Ti-containing compound, other sintering assistants may be
20 added, if necessary, whereby the nature of the sintered
product thereby obtainable, can be improved. As such
other sintering assistants, SiO2, ZrO2, Fe2O3, CaO and Y2O3
may, for example, be mentioned.
The above raw material mixture is thoroughly mixed
25 and pulverised. The mixing and pulverization of the raw
material mixture are not particularly limited and can be
carried out by known methods. For example, they may be

21
carried out by means of a ball mill, a medium-stirring
mill, etc. The pulverization degree of the raw material
mixture is not particularly limited, but the average
particle size is preferably at most 10 µm, particularly
5 preferably from 1 to 5 µm. The smaller the average
particle size of the raw material mixture, the better, so
long as it is within a range where no secondary particles
will be formed.
Molding assistants may preferably be incorporated to
10 the law material mixture. As such molding assistants,
known agents such as a binder, a pore-forming agent, a
release agent, a defoaming agent and a peptizer may be
employed. As the binder, polyvinyl alcohol, microwax
emulsion, methylcellulose or carboxymethylcellulose may,
15 for example, be preferred. As the pore-farming agent,
activated carbon, coke, a polyethylene resin, starch or
graphite may, for example, be preferred. As the release
agent, a stearic acid emulsion may, for example, be
preferred; as the defoaming agent, n-octyl alcohol or
20 octylphenoxyethanol may, for example, be preferred, and
as the peptizer, diethylamine or triethylamine may, for
example, be preferred.
The amounts of the molding assistants are not
particularly limited. However, in the case of the
25 present invention, they are preferably within the
following ranges, respectively, as calculated as solid
contents, per the total content of 100 parts by mass of

22
the Mg-containing compound, the Al-containing compound
and the Ti-containing compound to be used as the raw
materials, as calculated as the respective oxides.
Namely, it is preferred to use the binder in an amount of
5 from about 0.2 to about 0.6 part by mass, the pore-
forming agent in an amount of from about 20 to about 5O
parts by mass, the release agent in an amount of from
about 0.2 to about 0.7 part by maas, the deforming agent
in an amount of from about 0.5 to abot 1.5 parts by mass
10 and the peptizer in an amount of from about 0.5 to about
1.5 parts by mass.
The raw material mixture having such molding
assistants incorporated, is mixed, kneaded and
plasticized so that it is extrusion-processable, followed
15 by extrusion processing to form a honeycomb body. As the
method for extrusion, a known method may be used, and the
cross-sectional shape of each cell of the honeycomb may
be circular, oval, tetragonal or triangular. Further,
the entire configuration of the honeycomb body may be
20 either cylindrical or square tubular. The molded
honeycomb is preferably dried and then fired at from
1,000 to l,700º C preferably from l,250 to 1,450ºC. The
firing atmoephere is not particularly limited and is
preferably an oxygen-containing atmosphere such as in the
25 air which is commonly employed. The firing time is not
particularly limited so long as the firing can be done
until the eintering proceeds sufficiently, and it is

23
usually at a level of from 1 to 20 hours.
Also with respect to the temperature raising rate or
the temperature lowering rate at the time of the above
firing, there is no particular restriction, and such
5 conditions may be suitably set so that no cracks will be
formed in the obtainable sintered product. For example,
it is preferred to gradually raise the temperature
without rapid rise of the temperature to sufficiently
remove moisture, the molding assistants such as a binder,
10 etc. contained in the raw material mixture. Further, if
neceasary, prior to heating at the above-mentioned tiring
tamparature, presintering may be carried out preferably
within a temperature range of from 500 to 1,000ºC for
from 10 to 30 hours by mild temperature raise, whereby
15 the thermal stress in the sintered product during the
formation of aluminum magnesium titanate, can be relaxed,
and formation of cracks in the sintered product can be
suppressed.
The sintered product thus obtainable will be
20 aluminum magnesium titanate represented by the empirical
formula NgxAl2(1-x)Ti(1+x)O5 (wherein O component contained in an alkali feldspar is solid-
solubilized in the crystal lattice of aluminum magnesium
titanate. Such a sintered product has high heat
25 resistance and high thermal shock resistance and yet has
a crystal structure stabilized, as mentioned above, and
will thus be a wintered product having excellent

24
mechanical strength and high heat decomposition
resistance.
(B): Aluminum titanate sintered product
An aluminum titanate sintered product obtained by
5 firing at from 1,250 to l,700ºC a raw material mixture
comprising 100 parts by mass of the component X
comprising TiO2; and A12O3 in a molar ratio of the
former/the latter being 40 to 60/60 to 40, and from 1 to
10 parts by mass of the component y.
10 The above TiO2 and A12O3 to be used for forming
aluminum titanate may not necessarily be pure TiO2 and
A12O3, respectively, and they are not particularly
limited so long as they are components capable of
synthesizing aluminum titanate by firing. Such
15 components may usually be suitably selected among those
to be used as raw materials for various ceramics, such as
alumina ceramics, titania ceramics and aluminum titanate
ceramics. For example, a composite oxide, a carbonate, a
nitrate and a sulfate containing Al and Ti as metal
20 components may also be used.
TiO2 and Al2O3 are used in a molar ratio of the
former/the latter of 40 to 60/60 to 40, preferably 45 to
5 0/55 to 50. Particularly, when the molar ratio of
Al2O3/TiO2 is 1 or above within the above range, the
25 eutectic point of the sintered product can be avoided.
In the present invention, Al2O3 and TiO2 are used as a
mixture, and they will sometimes be collectively referred

25
to as component X.
In the case of the honeycomb carrier of the present
invention, it is necessary to add, in addition to the
above component X, the component Y as an additive. As
5 the alkali feldspar which is one member of the component.
Y, one represented by the empirical formula
(NayK1-y)AlSi3O8 is used. In the formula, y satisfies
XXX), preferably O.lXXX), particularly preferably
0.15XXX)0.85. An alkali feldspar having value y within
10 this range, has a low melting point and is particularly
effective for promoting the sintering of aluminum
titanate.
As the oxide of a spinel structure containing Mg
which is another member of component Y, MgAl2O4 or MgTi3O4
15 may, for example, be used. Such an oxide of a spinel
structure may be a natural mineral, or a substance
containing MgO and Al2O3, a substance containing MgO and
TiO2 or an oxide of a spine1 structure obtained by firing
such a substance. Further, a mixture of two or more
20 oxides of different spinel structure may be used.
Further, the MgO precursor is not limited so long as it
is capable of synthesizing MgO by firing, and it may, for
example, be MgCO3, Mg(NO3)2, MgSO4 or a mixture thereof.
The proportions of the component x and the component
25 Y are important. Prom 1 to 10 parts by mass of the
component Y is used per 100 parts by mass of the
component X. These proportions are proportions as oxides

26
of the components X and Y, respectively, and if a raw;
material other than an oxide is used, the proportion is
calculated as an oxide. If the proportion of the
component Y per 100 parts by mass of the component x is
5 smaller than 1 part by mass, the effect by addition of
the component Y will be insufficient to improve
characteristics of the sintered product. On the other
hand, if it exceeds 10 parts by mass, the amount of the
Si or Mg element will be considerably in excess of the
10 limit of solid-solubilization in the aluminum titanate
crystals, whereby the excessive added surplus component
will be present as an oxide by itself in the sintered
product, which may lead to a significant increase in the
thermal expansion coefficient. The proportion of the
15 component Y per 100 parts by mass of the component X is
particularly preferably from 3 to 7 parts by mass.
In the present invention, it is preferred to use as
the component Y a mixture of an alkali feldspar
represented by the empirical formula (NayK3-y)AlSi3O8, and
20 an oxide of a spiNel structure containing Mg and/or MgO
or its precursor, in combination. When such a mixture is
used, the above synergistic improvement of functions will
be achieved. In the mixture of an alkali feldspar, and
an oxide of a spinel structure containing Mg and/or MgO
25 or its precursor, the mass ratio of the former/the latter
is preferably 20 to 6O/80 to 40, particularly preferably
35 to 45/65 to 55. Within the above range, Si/Mg are

27
present in an equimolar ratio, and one of this range,
eynergistic effects by simultaneous solid-solubilization
of Si and Mg in aluminum titanate will hardly be obtained.
In the present invention, in addition to the above
5 components X and Y, if necessary, other sintering
assistants may be used, thereby the nature of the
sintered product thereby obtainable, can be improved. As
such other sintering assistants, SiO2, ZrO2, Fe2O3, CaO or
Y2O3, may, far example, be mentioned.
10 The raw material mixture comprising the components X
and Y is thoroughly mixed and pulverized. The mixing and
pulverization of the raw material mixture are not
particularly limited and can be carried out by known
methods. For example, they may be carried out by means
15 of a ball mill, a medium-stirring mill, etc. The
pulverisation degree of the raw material mixture is not
particularly limited, but the average particle size is
preferably at most 30 µm particularly preferably from 8
to 15 µm. The smaller the average particle size, the
20 better, so long as it is with in a range where no
secondary particles will be formed.
The amounts of molding assistants are not
particularly limited. However, in the case of the
present invention, they are preferably within the
25 following ranges, respectively, as calculated as solid
contents, per the total content of 100 parts by mass of
the component X and the component y (as calculated as

28
oxides) to be used as the raw materials. Namely, it is
preferred to use a binder in an amount of from about 0.2
to about 0.6 part by mass, a pore-forming agent in an
amount of from about 20 to about 50 parts by mass, a
5 release agent in an amount of from about 0.2 to about 0.7
part by mass, a deforming agent in an amount of from
about 0.5 to about 1.5 parts by mass and a peptizer in an
amount of from about 0.5 to about 1.5 parts by mass.
The raw material mixture having such molding
10 assistants incorporated, is mixed, Kneaded and
plasticized so that it is extrusion-pracessable, followed
by extrusion processing to form a honeycomb body. As the
method for extrusion, a known method may be used, and the
cross-sectional shape of each cell of the honeycomb may
15 be circular, oval, tetragonal or triangular. Further,
the entire configuration of the honeycomb body may be
either cylindrical or square tubular. The molded
honeycomb is preferably dried and then fired at from
1,250 to 1,700ºC, preferably from 1,300 to l,450ºC. The
20 firing atmosphere is not particularly limited and is
preferably an oxygen-containing atmosphere such as in the
air which is commonly employed. The firing time is not
particularly limited so long as the firing can be done
until the aintering proceeds sufficiently, and it is
25 usually at a level of from 1 to 20 hours.
Also with respect to the temperature, raising rate or
the temperature lowering rate at the time of the above

29
firing, there is no particular restriction, and such
conditions may be suitably set so that no cracks will be
formed in the obtainable sintered product. For example,
it is preferred to gradually raise the temperature
5 without rapid rise of the temperature to sufficiently
remove moisture, the molding assistants such as a binder,
etc. contained in the raw material mixture. Further, if
necessary, prior to heating at the above-mentioned firing
temperature, presintering may be carried out preferably
10 within a temperature range of from 500 to l,000ºC for
from 10 to 30 hours by mild temperature raise, whereby
the thermal stress in the sintered product during the
formation of aluminum titanate, can be relaxed, and
formation of cracks in the sintered product can be
15 suppressed.
The sintered product thus obtainable will be
aluminum titanata formed from the component X wherein the
5 1 component contained in an alkali feldspar and the Mg
component derived from an oxide of a spinel structure
20 containing Mg, MgO or a Mg-containing compound which can
be converted to MgO by firing, as the component Y, are
solid-solubilized in the crystal lattice of aluminum
titanate. Such a sintered product has high mechanical
strength, and a low thermal expansion coefficient and yet
25 has a crystal structure stabilized, as mentioned above,
and will thus be a sintered product having excellent
thermal decomposition resistance.

30
A. honeycomb body made of the above aluminum
magnesium titanate sintered product (A) or aluminum
titanate sintered product (B) has a thin wall honeycomb
structure having a wall thickness of e.g. from 0.05 to
5 0.6 mm and a cell density of e.g. from 15 to 124
cells/cm2. And, the porosity of the partition wall is
e.g. from 20 to 50%, and the thermal expansion
coefficient is e.g. at most 3.0xl0-6K-1. Such a honeycomb
body can be usad with stability, at from room temperature
10 to such a high temperature as above l,600°C as the
thermal decomposition reaction of aluminum magnesium
titanate or aluminum titanate is suppressed.
The honeycomb body is used as a carrier for a
catalyst to clean various exhaust gases containing
15 harmful components such as hydrocarbons, carbon monoxide,
NOx and SOx, particularly an exhaust gas of an automobile
containing NOx. Particularly, the honeycomb carrier of
the present invention is stable against an alkali at a
high temperature, whereby it is effective against an
20 exhaust gas of an automobile of a system wherein a fuel
is directly jetted into an engine or of a system wherein
a fuel is diluted and turned, an exhaust gas from which
contains NOx at a relatively high concentration.
As a catalyst supported by the carrier, various
25 known catalysts may be used such as a conventional so-
called three way catalyst to remove hydrocarbons and
carbon monoxide. However, the carrier of the present

31
invention is particularly effective for a catalyst
containing an alkali metal ox alkaline earth metal
component to remove NOx in an exhaust gas, The carrier
of the present invention is effective for a catalyst
5 containing potassium or barium effective for removal of
NOx, particularly potassium, amoivg alkali metals and
alkaline earth metals.
As a method of making the catalyst be supported by
the honeycomb body of the present invention, a known
10 means may be employed. When a catalyst is to be
supported, a material having a large specific surface
area, such as alumina or silica, may be interposed, as
the case requires, so as to improve the supporting ratio-
That is, alumina or silica may be supported by the
is honeycomb carrier, and a catalyst is supported fay alumina
or silica thus supported. The honeycomb body by which a
catalyst is supported, is preferably set in an can body
by means of a suitable supporting material.
20 EXAMPLE
NOW, the present invention will be described in
further detail with reference to Examples. However, it
should be understood that the present invention is by no
means thereby restricted.
35 EXAMPLE 1 1
To 100 parts by mass of a mixture comprising 26.7
mass% (2o mol%} of easily sinterable α-alumina, 62.8

32
maes% (60 mol%) of anatase-type titanium oxide and 10.5
mass% (2 0 mol%) of periclase-type magnesium oxide present
as a natural mineral, 4 parts by mass of an alkali
feldspar represented "by (Na0-6K0-4)AlSi3O8, 0.25 part by
5 mass of polyvinyl alcohol as a binder, 1 part by mass of
diethylamine as a peptizer, 0.5 part by mass of
polypropylene glycol as a defoaming agent, and 35 parts
by mass of activated carbon having a particle size of at
most 30 µm as a. pore-forming agent, were added and mixed
in for 3 hours in a ball mill and then dried in a dryer at
120°C for at least 12 hours to obtain a raw material
powder.
The obtained raw material powder was pulverized to
an average particle size of about 5 µm and extruded, by a
IS vacuum extruder (manufactured by Miyazaki Iron Works Co.,
Ltd.) to obtain a cylindrical honeycomb body having a
diameter of 129 mm and a length of 150 mm, and having
cross-sectianally square cells with a wall thickness of
0.1 mm and a. cell density of 93 cells/cm2 . This
20 honeycomb body was dsied and then, fired in the atmosphere
at 1,400°C fox 4 hours and then left to cool, to obtain a
sintered product.
A honeycomb sintered product made of an aluminum
25 magnesium citanata sintered product was obtained in. the.
same manner as IN Example 1-1 except that no alkali
feldspar was used.

33
COMPARATIVE EXAMPLE 1-2
A honeycomb having the game shape as that in Example
1 -1 -was prepared by using as the material for a honeycomb
carrier a cordierite powder (2MgO-2Al2O3.5SiO2) by a known
5 method.
PROFERTY TESTS WITH RESPECT TO HOMEYCOMB SINTERED
PRODUCTS
With respect to the honeycomb sintered products
obtained in the above Example l-l and Comparative
10 Examples 1-1 and 1-2, the porosity (%), the thermal
expansion coefficient (x10-6K-1) at from room temperature
to 800°C, the thermal shocK resistance (°C) by an in-
water dropping method, the softening temperature (°C) and
the compression strength (MPa) were measured, and the
15 results are shown in Table 1-1. Here, the porosity was
measured by a method in accordance with JIS R1634, the
thermal expansion coefficient by a method in accordance
with JIS R1618, the thermal shock resistance by a method
in accordance with JIS R1648, the softening temperature
20 by a method in accordance with JIS R2209, and the
compression strength by a method in accordance with JIS
R1608, Further, with respect to the compression strength,
from each honeycomb sintered product* a square test
specimen having cross-sectionally 5x5 cells and a length
25 of 15 mm, was cut out, and tnis specimen was measured
from three directions i.e. (A) in the lengthwise axial
direction (axial), (B) in the vertical direction

34
(tangential) and (C) in the direction inclined by 45°
from the lengthwise axis (diagonal).

TABLE 1-1
Porosity(%) Thermalexpansioncoefficient(10-6K-1) Thermalshockresistance Softeningtemperature Compression strength(MPa)
(A) (B) (C)
Example 1-1 34 1.0 850 1580 >14 >3 >2
ComparativeExample 1-1 35 0.2 860 1600 >9 >1.5 >0.2
ComparativeExample 1-2 35 0.6 650 1320 >10 >1.3 >0.2

36
THERMAL DECOMPOSITION RESISTANCE TEST
From the honeycomb carrier in Example 1-1, a test
specimen of 10 mm x 10 mm x 10 mm was cut out and held in
a high temperature atmosphere of 1,100°C, whereby the.
5 change with time of the remaining ratio α (%) of aluminum
magnesium titanate was investigated to carry out a
thermal decomposition resistance test.
Here, the remaining ratio of aluminum magnesium
titanate was obtained by the following method from the
10 spectrum of the X-ray diffraction measurement (XRD) ,
Firstly, as MgAl2O4 (spinel) and TiO2 (rutile) are
formed when aluminum magnesium titanate undergoes thermal
decomposition, by using the integrated intensity
(IT102(110)) of the diffraction peak at the (110) face of
is rutile and the integrated intensity (IMAT(023)) of the
diffraction peak at the (023) face of aluminum magnesium
ticanate, the intensity ratio R of aluminum magriesium
titanate to rutile was obtained by the following formula:
R= IMAT(023) / ( IMAT(023) + ( IT102 (110) )
20 Further, also with respect to the sintered product
before carrying out the thermal treatment at l,l00°c, the
intensity Ratio R0 of aluminum magnesium titanate to
rutile was obtained in the same manner. Then, using R
and R0 obtained as described above, the remaining ratio α
25 (%) of aluminum magnesium titanate was obtained by the
following formula;
α=(R/R0) x 100

37
With respect to the respective sintered products in
Example 1-1 and Comparative Example 1-1, the changes with
time of the remaining ratio a of aluminum magnesium
titanate are shown by a graph in Fig. 1. AS is evident
5 from Fig. 1, the sintered product in Example 1-1 is
superior in the thermal decomposition resistance, as the
remaining ratio α of aluminum magnesium titanate is
maintained at a high level over a long time, as compared
with the sintered product in Comparative Example 1-1.
10 ALKALI RESISTANCE TEST WITH RESPECT TO HONEYCOMB BODIES
The following test was carried out to examine the
corrosion resistance of the honeycomb bodies against a
potassium-containing catalyst which is a catalyst for
removal of NOx in an exhaust gas of an automobile. A
15 honeycomb carrier against an exhaust gas of an automobile
is used at a temperature of from room temperature to
850°C, and the potassium concentration of the potassium-
Containing catalyse is not so high. However, in this
test, an accelerated test under severe conditions was
20 carried out, which comprises dipping a test specimen in
an aqueous potassium nitrate solution at a concentration
of 1 mol/liter, drying it and holding it in a furnace
maintained at a temperature of 900°C for a long period of
time.
25
TEST METHOD
From each of the honeycomb bodies in Example 1-1 and

38
Comparative Example 1-2, a test specimen with, a 30 mm
square cross section and a length of 50 mm was cut out,
and the test specimen was dipped in an aqueous potassium
nitrate solution at a concentration of 1 mol/liter at
5 room temperature for l hour, and then dried at 70°C for 1
hour- The dried honeycomb body was inserted into a
tubular furnace with, an inner diameter of 5 cm and a
length of 42 cm and held for a predetermined time under
the following conditions while supplying the air
10 containing 10% of moisture to the tubular furnace at 25
cc/min. Then, the honeycomb body taken out from the
tubular furnace was subjected to XRD measurement to
examine degeneration of the honeycomb body material. The
air containing 10% of moisture to be supplied to the
15 tubular furnace was prepared by making the air pass
through a water tank controlled at 60°C. The results of
the test are shown, in Table 1-2,
Holding conditions:
Temperature in the furnace: 900°C, temperature-
20 raising and lowering rate of the furnace: l00oC/hr,
holding time: 50 hours, 100 hours, 150 hours or 200 hours

39
TABLE 1-2
Holding time
50 hours 100 hours 150 hours 200 hours
Honeycombbody inExample 1-1 No change No change No change No change
Honeycombbody inComparativeEXample 1-2 No change Peak ofKAlSiO4observedin thevicinityOf **29-28° Peak ofKAlSiO4 Peak ofKAlSiO4improved
As is evident from the results shown in Table 1-2,
the honeycomb body in Example 1-1 has a great corrosion
5 resistance to potassium, as compared with the honeycomb
body in Camparative Example 1-2.
EXAMPLE 2-1
To 100 parts fey mass of a mixture comprising 56,1
mass% (50 mol%} of easily sinterable α-alumina and 43.9
10 mass% (50 mol%) of anatase-type ticanium oxide, 4 parts
by mass of an alkali feldspar represented by
(Na0.6K0.4)AlSi3O2 as an additive, 0.25 part by mass of
polyvinyl alcohol as a binder, 1 part by mass of
diethylamine as a peptizer, 0.5 part by mass of
15 polypropylene glycol as a defeaming agent, and 35 parts
by mass of activated carbon having a particle size of
from 50 to 80 µm as a pore-forming agent, were added and
mixed for 3 hours in a ball mill and then dried in a
dryer at 120°C for at least 12 hours to obtain a raw
20 material povder.

40
The obtained raw material powder was pulverised to
an average particle. size of about 5 µm and extruded by a
vacuum extruder (manufactured by Miyazaki Iran. Works CO.,
Ltd.) to obtatin a cylindrical honeycomb body having a
5 diameter of 12 9 mm and a length of 150 mm, and having
cross-sectionally square cells with a wall thickness of
0.1 mm and a cell density of 93 cells/cm2. This
honeycomb body was dried and then fired in the atmosphere
at l,400°c for. 4 hours and then left to cool, to obtain a
10 honeycomb body.
COMPARATIVE EXAMPLE 2-1
A honeycomb carrier made of an aluminum titanate
sintered product was obtained in the same manner as in
Example 2-1 except that no alkali feldspar was used.
15 COMPARATIVE EXAMPLE 2-2
A honeycomb carrier having the same shape as that in
Example 2-1 was prepared by using a cordierite powder
(2MgO-2Al2O3-5SiO2) by a known method,
EXAMPLE 2-2
20 To 100 parts by mass of a mixture comprising 56.1
mass% (50 mol%) of easily sinterable α-alumina and 43.9
mass% (50 mol%) of anatage-type titanium oxide, 4 parts
by mass of an alkali feldspar represented by
(Na0.6K0.4) AlSi3O8 and 6 parts by mass of a spinel compound
25 represented by the formula MgAl2O4 as additives, 0.25
part by mass of polyvinyl alcohol as a binder, 1 part by
mass of diethylamine as a peptizer, 0.5 part by mass of

41
polypropylene glycol as a defoaming agent, and 35 parts
by mass of activated carbon having a particle size of
from 30 to 80 µm as a pore-forming agent, were added and
mixed for 3 hours in a ball wil1 and then dried in a
5 drier at 120°c for at least 12 hours to obtain a raw
material powder.
Using the obtained raw material powder,
pulverization, extrusion molding, drying and firing were
carried out in the same manner as in Example 2-1 to
10 obtain a honeycomb carrier.
EXAMPLE 2-1
To 100 parts by mass of a mixture comprising 56.1
mass% (50 mol%} of easily sinterable α-alumina and 43.9
mass* (50 mol%) of anatase-type titanium oxide, 6 parts
15 by mass of a spinel compound represented by the formula
MgAl2O4 as an additive, 0.25 part by mass of polyvinyl
alcohol as a binder, l part by mass of diethylamine as a
peptizer, 0.5 part by mass of polypropylene glycol as a
defoaming agent, and 35 parts by mass of activated carbon
20 having a particle size of from 5O to 80 µm as a pore-
forming agent, were added and mixed for 3 hours in a ball
mill and then dried in a drier at 120°C for at least 12
hours to obtain a raw material powder.
Using the obtained raw material powder,
35 pulverization, extrusion molding, drying and firing were
carried out in the same manner as in Example 2-1 to
obtain a honeycomb carrier.

42
PROPERTY TESTS WITH RESPECT TO HONEYCOMB SINTERED
PRODUCTS
With respect to the honeycomb sintered products
obtained in the above Examples 2-1, 2-2 and 2-3 and
5 Comparative Examples 2-1 and 2-3, the porosity (%), the
thermal expansion coefficient (X 10-6K-1) at from room
temperature to 800°C, the thermal shock resistance (°C)
by an in-water dropping method, the softening temperature
(°C) and the compression strength (MPa) were measured,
10 and the results are shown in Table 2-1. Here, the
porosity was measured by a method in accordance with JIS
Rl634, the thermal expansion coefficient by a method in
accordance with JIS R1618, the thermal shock resistance
by a method in accordance with JIS R1648, the softening
15 temperature by a method in accordance with JIS R2209, and
the compression strength by a method in accordance with
JIS R1608. Further, with respect to the compression
strength, from each honeycomb sintered product, a square
test apecimen having cross-sectionally 5x5 cells and a
20 length of 15 mm, was cut out, and this specimen was
measured from three directions i.e. (A) in the lengthwise
axial direction (axial), (B) in the vertical direction
(tangential) and (C) in the direction inclined by 45°
from the lengthwise axis {diagonal).



44
As is evident from Table 2-1, each of the honeycomb
carriers in Examples 2-1, 2-2 and 2-3 has a compression
strength sufficient for practical use. The honeycomb
carrier in Comparative Example 2-1 has low strength
5 insufficient for practical use, and the honeycomb carrier
in Comparative Example 2-2 has a low softening
temperature and is thereby poor in heat resistance.
THERRMAL DECOMPOSITION RESISTANCE TEST
From each of the honeycomb carriers in Examples 2-1
10 and 2-2 and Comparative Example 2-1, a test specimen of
10 mm x lo mm x 10 mm was cut out and held in a high
temperature atmosphere of 1,000°C whereby the change
with time of the remaining ratio β(%) of aluminum
titanate was investigated to carry out a thermal
AS decomposition resistance test.
Here, the remaining ratio of aluminum titan-ate was
obtained by the following method from the specturm of the
X-ray diffraction measurement (XRD).
Firstly, as Al2O3 (corundum] and TiO2 {rutile} are
20 formed when alutninum titanate undergoes thermal
decomposition ueirng the integrated intensity (IT120 (110))
of the diffraction peak at the (110) face of rutile and
the integrated intensity (IAT(023)) of the diffraction peak
at the (023) face of aluminum titanate, the intensity
25 ratio r of aluiminum titanate to rutile was obtained by
the following formula:


45
Further, also with respect to the sintered product
before carrying out the thermal treatment at 1,000°C, the
intensity ratio r0 of aluminum, titanate to rutile was
obtained in the same manner. Then, using r and rc
5 obtained as described above, the remaining ratio β(%) of
aluminum titanate was obtained by the following formula:
β= (r/ro) x 100
With respect to the respective honeycomb shape
sintered products in Examples 2-1 and 2-2 and Comparative
10 Example 2-1, the changes with time of the remaining ratio
β of aluminum titanate are shown by a graph in Fig, 2,
As is evident from. Fig, 2, Examples 2-1 and 2-2 are
supperior in the thermal decomposition resistance, as the
remaining ratio is maintained at a high level over a long
is time, as compared with Comparative Example 2-1. Further,
it is evident that while the remaining ratio in Example
2-1 after expiration of 100 hours in Fig. 2 is slightly-
low, the remaining ratio in Example 2-2 is still remained
at a high level and thus shown that the thermal
20 decomposition resistance is further excellent over
Example 2-1.
ALKALI RESISTANCE TEST WITH RESPECT TO HONEYCOME BODIES
The following test was carried out to examine the
corrosion resistance of the honeycomb bodies against a
25 potassium-containing catalyst which is a catalyst for
removal of NOx in an exhaust gas of an automobile. A
honeycomb carrier against an exhaust gas of an automobile

45
is used at a temperature of from room temperature to
850oC, and the potassium concentration of the potaseium-
containing catalyst is not so high. However, in this
test, an accelerated test under severe conditions was
5 carried out, which comprises dipping a test specimen in
an aqueous potassium nitrate solution at a concentration
of 1 mol/liter, drying it and holding it in a furnace
maintained at a temperature of 900°C for a long period of
time,
10 TEST METHOD
From each of the honeycomb bodies in Examples 2-1
and 2-2 and Comparative Example 2-2, a test specimen with
a 30 mm sguare cross section and a length of 5 0 mm was
cut out, and the test specimen was dipped in an aqueous
15 potassium nitrate solution, at a concentration of 1
mol/liter at room temperature for 1 hour, and then dried
at 70°c for 1 hour. The dried honeycomb body was
inserted into a tubular furnace with an inner diameter of
5 cm and a length of 42 cm and held for a predetermined
20 time under the following conditions while supplying the
air containing 10% of moisture to the tubular furnace at
25 cc/min. Then, the honeycomb body taken out from the
tubular furnace was subjected to XRD measurement to
examine degeneration of the honeycomb body material. The
25 air containing 10% of moisture to be supplied to the
tubular furnace was prepared by making the air pass
through a water tank controlled at 60°C. The results of

47
the teat are shown in Table 2-2.
Holding conditions:
Temperature in the furnace: 900°C, teraperature-
raising and lowering rate of the furnace: 100°C/hr,
5 holding time; 50 hours, 100 hours, 150 hours or 200 hours
TABLE 3-2
Honeycombbody Holding time
50 hours 100 hours 150 hours 200 hours
Example 2-1 No change No change No change No change
Example 2-2 No change No change No change No change
ComparativeExample 2-2 No change Peak ofKAlSiO4observedin. thevicinityof **2^=28° Peak ofKAlSiO4improved Peak ofKAlSiO4improved
As is evident- from results shown in Table 2-2, each
of the honeycomb carriers in Examples 2-1 and 2-2 is
10 excellent in corrosion resiacance to an alkali.

48
CLAIMS:
1. A honeycomb carrier for an exhaust: gas-cleaning
catalyst which is a honeycomb carrier to support a
catalyst to clean an exhaust gas, characterised in that
5 the material for the honeycomb carrier is an aluminum
magnesium titanate sintered product obtained by firing at
from 1,000 to l,700°C a mixture comprising 100 parts by
mass, as calculated as oxides, of a mixture comprising a
Mg-containing compound, an Al-containing compound and a
10 Ti-containing compound in the same metal component ratio
as the metal component ratio of Mg, Al and Ti in an
aluminum magnesium titanate represented by the empirical
formula MgxAl2(1-x)Ti(1-x)O5 (wherein 0 10 parts by mass of an alkali feldspar represented by the
15 empirical formula (Nayk1-y)AlSi3O8 (wherein XXX).
2 . A honeycomb carrier for an exhaust gas-cleaning
catalyst which is a honeycomb carrier to support a
catalyst to clean an exhaust gas, characterized in that
the material for the honeycomb carrier is an aluminum
20 titanate sintered product obtained by firing at from
1,250 to 1,700°C a raw material mixture comprising 100
parts by mass of a mixture (hereinafter referred to as
component X) comprising TiO2 and Al2O3 in a molar ratio of
the former/the latter being 40 to 60/60 to 40, and from 1
25 to 10 parts by mass of an alkali feldspar represented by
the empirical formula. (NayK1-y)AlSi3O8 (wherein XXX), an
oxide of a spinel structure containing Mg, or MgO or a

49
Mg-containing compound which can be converted to MgO by
firing (hereinafter referred to as component Y).
3. The honeycomb carrier for an exhaust gas-cleaning
catalyst according to Claim 2, wherein the component Y is
5 a mixture comprising an alkali feldpar represented by
(Nayk1-y) Alsi3O8 (wherein XXX) , and an oxide of a spinel
structure containing Mg and/or MgO or a Mg-containing
compound which can be converted to MgO by firing.
4, The honeycomb carrier for an exhaust gas-cleaning
10 catalyst according to any one of Claims 1 to 3 , which has
a wall thickness of from 0.05 to 0.6 mm, a cell density
of from 15 to 124 cells/ cm2, a porosity of the partition
wall of from 20 to 50%, and a thermal expansion
coefficient of at most 3.0x10-6K-1.
15 5. The honeycomb carrier for an exhaust gas-cleaning
catalyst according to any one of Claims 1 to 4, wherein
the catalyst contains an alkali metal or alkaline earth
metal component to remove NOx in the exhaust gas_
6, The honeycomb carrier for an exhaust gas-cleaning
20 catalyst according to any one of Claims 1 to 5, wherein
the exhaust gas is an exhaust gas of an automobile of a
system wherein a fuel is directly jetted, into an engine
or of a system wherein a fuel is diluted and burned.
7. A process for producing honeycomb carrier for an
as exhaust gas-cleaning catalyst, characterized by preparing
a raw material mixture comprising 100 parts by mass, as
calculated as oxides, of a mixture comprising a Mg-

50
containing compound, an Al-containing compound and a Ti-
containing compound in the same metal component ratio as
the metal component ratio of Kg, Al and Ti in an aluminum
magnesium titanate represented by the empirical formula
5 MgxAl2(1-x)Ti(1-x)O5 (Wherein 0 by mass of an alkali feldspar represented by the
empirical formula (NayK1-y)Alsi3O9 (wherein XXX), adding
a molding assistant to the raw material mixture, followed
by kneading to plasticize the raw materia1 mixture to
10 make it extrusion-processable, and then extrusion
processing it into a honeycomb body, followed by firing
at from 1,000 to 1,700°C.
8. A process for producing a honeycomb carrier for an
exhaust gas-cleaning catalyst, characterized by preparing
15 a mixture comprising 100 parts by mass of a mixture
(hereinafter referred to as component X) comprising TiO2
and Al2O3 in a molar ratio of the former/the latter being
40 to 60/60 to 40, and from 1 to 10 parts by mass of an
alkali feldspar represented by the empirical formula
20 (NayK1-y)AlSi3O8 (where in XXX), an oxide of a spinel
stmacture containing Mg, or MgO or a Mg-containing
compound which can be converted to MgO by firing
(hereinafter referred to as component Y) , adding a
molding assistant to the mixture, followed by kneading to
25 plasticize the mixture to make it extrusion-processable,
and extrusion processing it into a honeycomb body,
followed by firing at from 1,250 to 1,700°C.

51
9. The process for producing a honeycomb carrier for an
exhaust gas-cleaning catalyst according to Claim 7 or 8,
wherein the average particle size of each component
contained in the raw material mixture is at most 10 µm.
5 10 . A method for cleaning an exhaust gas, which
comprises contacting the exhaust gas to a honeycomb
carrier supporting a catalyst to clean an exhaust gas,
characterized in that the material for the honeycomb
carrier is an aluminum magnesium titanate sintered
10 product obtained by firing at from 1,000 to l,700°C a
mixture comprising 100 parts by mass, as calculated as
oxides, of a mixture comprising a Mg-containing compound,
an Al-containing compound and a Ti-containing compound in
the same metal component ratio as the metal component
is ratio of Mg, Al and Ti in an aluminum magnesium titanate
represented by the empirical formula MgxAl2(3-x)Ti(1+x)O5
(wherein 0 alKali feldspar represented by the empirical formula
(NayK1-y)AlSi308 (wherein XXX).
20 11. A method for cleaning an exhaust gas, which
comprises contacting the exhaust gas to a honeycomb
carrier supporting a catalyst to clean an exhaust gas,
characterized in that the material for the honeycomb
carrier is an aluminum titanate sintered product obtained
25 by firing at from 1,250 to l,700°C a raw material mixture
comprising 100 parts by mass of a mixture (hereinafter
referred to as component X) comprising TiO2 and A12O3 in a

52
molar ratio of the former/the latter being 40 to 60/60 to
40, and from 1 to 10 parts by mass of an alkali feldspar
represented by the empirical formula (NayK1-y)AlSi3O8
(wherein XXX) , an oxide of a spinel structure
5 containing Mg, ox MgO or a Mg-containing conpound which
can be converted to MgO by firing (hereinafter referred
to as component Y).

to provide a honeycomb carrier to support a catalyst
to clean e.g. an exhaust gas of an automobile
particularly containing NOx, which is excellent in heat
5 resistance, thermal shock, resiatance, mechanica1 strength
and thermal decomposition resistance and has a great
corrosion resistance to a catalyst, and is thus capable
of being used with stability for a long period of time,
and a procege for its production.
10 The material for the honeycojnb carrier is an
aluminum magnesium titanate sintered product obtained by
firing at from 1,000 to l,700°C a molded product formed
from a raw material mixcture eomprising 100 parts by mass,
as calculated as oxides, of a mixture comprising a Mg-
15 containing compound, an Al-containing compound and a Ti-
containing compound in the same metal component ratio as
the metal component ratio ot Mg, Al and Ti in an aluminium
magnesium titanate represented by the empirical formula
MgxAl2(1+x)Ti(1+x)O5 fwherein 0 20 by mass of an alkali feldspar represented by the
empirical formula (NayK1-y)AlSi3O8 (wherein XXX) .

Documents:


Patent Number 224197
Indian Patent Application Number 00217/KOLNP/2006
PG Journal Number 41/2008
Publication Date 10-Oct-2008
Grant Date 03-Oct-2008
Date of Filing 30-Jan-2006
Name of Patentee OHCERA CO., LTD
Applicant Address 1-19, UCHIHONMACHI 2-CHOME, CHUOU-KU, OSAKA-SHI, OSAKA
Inventors:
# Inventor's Name Inventor's Address
1 FUKUDA TSUTOMU 785-1, KUNIKANE, KUMISO-CHO, KAKOGA WA-SHI, HYOGO 6751213
2 FUKUDA MASAHIRO 95-1-603, OCHIAI, MAKISHIMA-CHO, UJI-SHI KYOTO 6110041
3 FUKUDA MASAAKI 785-1, KUNIKANE, KAMISO-CHO, KAKOGAWA-SHI, HYOGO 6751213
4 YOKO TOSHINOBU 31-1-120, TODOMONNOMAE, UJI-SHI, KYOTO 6110013
5 TAKAHASHI MASAHIDE KYODAI SHOKUINSHUKUSHA 1-113, GOKASHO KANYUCHI, UJI-SHI, KYOTO 6110011
PCT International Classification Number C04B 35/478
PCT International Application Number PCT/JP2004/011203
PCT International Filing date 2004-07-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2003-203271 2003-07-29 Japan
2 2003-321537 2003-09-12 Japan